This invention relates to a "comprex" supercharger for internal combustion engines, and more particularly to a control system for controlling a "comprex" supercharger of this kind, which is capable of controlling the supercharger so as to achieve supercharging pressure optimum to operating conditions of the engine.
Among known superchargers for internal combustion engines, particularly diesel engines, is a "comprex" supercharger which is adapted to compress air directly by exhaust gas pressure and then supplies the compressed air as intake air to the engine. Such "comprex" supercharger typically comprises a rotor formed along its whole periphery with a plurality of axially extending cells arranged circumferentially of the rotor, an exhaust gas inlet arranged opposite the cells at one end of the rotor, an air inlet arranged opposite the cells at the other end of the rotor, and drive means drivingly coupling the rotor to an internal combustion engine for rotating the rotor. Fresh air through the air inlet is introduced into the cells at the one end of the rotating rotor and compressed by the pressure of engine exhaust gas introduced into the cells at the other end of the rotor, and the compressed air, is supplied to the engine. However, such conventional "comprex" supercharger has the drawback that while the propagation velocity of pressure-shock wave of exhaust gas in the cells is variable depending upon operating conditions of the engine, the rotor is rotated with a constant speed ratio to the engine speed, thereby failing to obtain optimum supercharging pressure to operating conditions of the engine.